LTC3557

LTC3557/LTC3557-1 USB Power Manager with Li-Ion Charger and Three Step-Down Regulators FEATURES ■ Seamless Transition Between Input Power Sources: Li-Ion Battery, USB, 5V Wall Adapter or High Voltage Buck Regulator with Bat-TrackTM ■ 200mΩ Internal Ideal Diode Plus Optional External Ideal Diode Controller Provides Low Loss Power Path When Input Current is Limited or Unavailable ■ Triple Adjustable High Efficiency Step-Down Switching Regulators (600mA, 400mA, 400mA IOUT) ■ Pin Selectable Burst Mode® Operation ■ Full Featured Li-Ion/Polymer Battery Charger ■ 1.5A Maximum Charge Current with Thermal Limiting ■ Battery Float Voltage: 4.2V (LTC3557) 4.1V (LTC3557-1) ■ Low Profile 4mm × 4mm 28-Pin QFN Package APPLICATIONS ■ HDD-Based MP3 Players ■ PDA, PMP, PND/GPS ■ USB-Based Handheld Products DESCRIPTION The LTC®3557/LTC3557-1 is a highly integrated power management and battery charger IC for single cell Li-Ion/ Polymer battery applications. It includes a PowerPathTM manager with automatic load prioritization, a battery charger, an ideal diode and numerous internal protection features. Designed specifically for USB applications, the LTC3557/LTC3557-1 power manager automatically limits input current to a maximum of either 100mA or 500mA for USB applications or 1A for wall adapter powered applications. Battery charge current is automatically reduced such that the sum of the load current and the charge current does not exceed the programmed input current limit. The LTC3557/LTC3557-1 ...